High Moisture Barrier Coextruded Blown Film and Laminate and Package Made Therefrom

ABSTRACT

A coextruded multilayer blown film includes a core layer including a blend of ethylene vinyl alcohol copolymer and an active oxygen barrier composition including a blend of a thermoplastic resin having carbon-carbon double bonds substantially in its main chain, a transition metal salt, and an oxygen barrier polymer; two intermediate layers each including polyamide; a first outer layer including high density polyethylene; a second outer layer including olefinic polymer; and two tie layers each adhering an intermediate layer to the first and second outer layers respectively; wherein from 20% to 65% by weight of the coextruded multilayer blown film is made up of high density polyethylene. A package includes a food product in a hermetic pouch made from the coextruded film, optionally adhered to a PET film, such as a printed, or trap-printed PET film, to form a laminate, the pouch having a longitudinal seal and transverse heat seals.

FIELD OF THE INVENTION

The invention relates to a coextruded blown film for use in packaging, such as food packaging, such as in aseptic, hot-fill, or retort packaging environments, and a laminate and package made therefrom.

BACKGROUND OF THE INVENTION

Polymeric films, such as blown polymeric films, are well known for use in packaging foods.

Sometimes a sterile food product is placed in a sterilized container such as a pouch. The food product is thus preserved for later storage or use. Various methods of sterilizing the container, and filling the container with a pasteurized product, are known. This is known as an aseptic food packaging process.

Sometimes a pouch material is used to package a product, such as an aqueous or liquid food product, where the product is at an elevated temperature of 170° F. to 210° F. This is known as a hot fill process.

Sometimes a pouch, after filling with a food product, is exposed to retort (high temperature) conditions. This is known as a retort process.

Aseptic, hot fill, retort, and other packages can be made in a vertical form/fill/seal process. Vertical form/fill/seal (VFFS) packaging systems have proven to be very useful in packaging a wide variety of pumpable products. The VFFS process is known to those of skill in the art, and described for example in U.S. Pat. No. 4,589,247 (Tsuruta et al), incorporated herein by reference. A pumpable product is introduced through a central, vertical fill tube to a formed tubular film having been sealed transversely at its lower end, and longitudinally. The pouch is then completed by sealing the upper end of the tubular segment, and severing the pouch from the tubular film above it.

Shelf-stable packaging materials, e.g. in the form of stand-up pouches, are growing in the marketplace. These materials need both high oxygen and high moisture barrier performance. Materials currently in the marketplace typically employ aluminum foil, metallization of a substrate such as PET with aluminum, or the use of alumina or silica coatings on PET or other substrates

These materials are typically not transparent, however, and thus prevent the packager or consumer from clearly viewing the contained product. The presence of metal in the packaging material can also prevent the reheating of the contained product in a microwave oven, or the use of a metal detector during QC inspection of the package. Metallic packaging is also susceptible to flex cracking and subsequent deterioration of barrier properties.

The invention comprises a coextruded multilayer blown film that provides high moisture barrier (i.e. low moisture vapor transmission rate), high oxygen barrier (i.e. low oxygen transmission rate), as well as good impact strength as measured by instrumented impact methods, and good elastic modulus properties. The film utilizes a combination of a specific range of high density polyethylene (HDPE) in the overall film composition, and a blend of ethylene vinyl alcohol copolymer (EVOH) and an active oxygen barrier composition. In one embodiment, relatively small, shelf-stable retail pouches can benefit from the use of the inventive film in such applications.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, a coextruded multilayer blown film-comprises a core layer comprising a blend of ethylene vinyl alcohol copolymer, and an active oxygen barrier composition comprising a blend of a thermoplastic resin having carbon-carbon double bonds substantially in its main chain, a transition metal salt, and an oxygen barrier polymer; a first and second intermediate layer each comprising polyamide; a first outer layer comprising high density polyethylene; a second outer layer comprising an olefinic polymer; a first tie layer adhering the first intermediate layer to the first outer layer, and a second tie layer adhering the second intermediate layer to the second outer layer; wherein from 20% to 65% by weight of the coextruded multilayer blown film comprises high density polyethylene.

In a second aspect of the present invention, a package comprises a food product, and a hermetic pouch in which the food product is disposed, the hermetic pouch having a longitudinal seal and transverse heat seals, the pouch comprising a coextruded multilayer blown film comprising a core layer comprising a blend of ethylene vinyl alcohol copolymer, and an active oxygen barrier composition comprising a blend of a thermoplastic resin having carbon-carbon double bonds substantially in its main chain, a transition metal salt, and an oxygen barrier polymer; a first and second intermediate layer each comprising polyamide; a first outer layer comprising a high density polyethylene; a second outer layer comprising an olefinic polymer; a first tie layer adhering the first intermediate layer to the first outer layer, and a second tie layer adhering the second intermediate layer to the second outer layer; wherein from 20% to 65% by weight of the coextruded multilayer blown film comprises high density polyethylene.

In a third aspect of the present invention, a package comprises a food product, and a hermetic pouch in which the food product is disposed, the hermetic pouch having a longitudinal seal and two transverse heat seals, the pouch comprising a laminate comprising a) a coextruded multilayer blown film comprising a core layer comprising a blend of ethylene vinyl alcohol copolymer, and an active oxygen barrier composition comprising a blend of a thermoplastic resin having carbon-carbon double bonds substantially in its main chain, a transition metal salt, and an oxygen barrier polymer; a first and second intermediate layer each comprising polyamide; a first outer layer comprising a high density polyethylene; a second outer layer comprising an olefinic polymer; a first tie layer adhering the first intermediate layer to the first outer layer, and a second tie layer adhering the second intermediate layer to the second outer layer; wherein from 20% to 65% by weight of the coextruded multilayer blown film comprises high density polyethylene; and b) a trap-printed film comprising polyethylene terephthalate, the trap-printed film adhesively joined to the first outer layer of the coextruded multilayer blown film.

DEFINITIONS

“Aseptic” herein refers to a process wherein a sterilized container or packaging material, e.g. a pre-made pouch or a pouch constructed in a vertical form/fill/seal process, is filled with a sterilized food product, in a hygienic environment. The food product is thus rendered shelf stable in normal nonrefrigerated conditions. “Aseptic” is also used herein to refer to the resulting filled and closed package. The package or packaging material, and the food product, are typically separately sterilized before filling.

“High density polyethylene” is an ethylene homopolymer or copolymer with a density of 0.940 g/cc or higher.

“Ethylene/alpha-olefin copolymer” (EAO) herein refers to copolymers of ethylene with one or more comonomers selected from C₃ to C₁₀ alpha-olefins such as propene, butene-1, hexene-1, octene-1, etc. in which the molecules of the copolymers comprise long polymer chains with relatively few side chain branches arising from the alpha-olefin which was reacted with ethylene. EAO includes such heterogeneous materials as linear medium density polyethylene (LMDPE), linear low density polyethylene (LMDPE), and very low and ultra low density polyethylene (VLDPE and ULDPE), such as DOWLEX™ and ATTANE™ resins supplied by Dow, and ESCORENE™ resins supplied by Exxon; as well as linear homogeneous ethylene/alpha olefin copolymers (HEAO) such as TAFMER™ resins supplied by Mitsui Petrochemical Corporation, EXACT™ and EXCEED™ resins supplied by Exxon, long chain branched (HEAO) AFFINITY™ resins and ELITE™ resins supplied by the Dow Chemical Company, ENGAGE™ resins supplied by DuPont Dow Elastomers, and SURPASS™ resins supplied by Nova Chemicals.

“Ethylene homopolymer or copolymer” herein refers to ethylene homopolymer such as low density polyethylene; ethylene/alpha olefin copolymer such as those defined herein; ethylene/vinyl acetate copolymer; ethylene/alkyl (meth)acrylate copolymer; ethylene/(meth)acrylic acid copolymer; or ionomer resin.

“Olefinic polymer” and the like herein refers to a polymer or copolymer derived at least in part from an olefinic monomer.

“Polyimide” herein refers to polymers having amide linkages along the molecular chain, and preferably to synthetic polyamides such as nylons.

“Polymer” and the like herein means a homopolymer, but also copolymers thereof, including bispolymers, terpolymers, etc.

All compositional percentages used herein are presented on a “by weight” basis, unless designated otherwise.

DETAILED DESCRIPTION OF THE INVENTION Film Embodiments of the Invention

A representative film structure of embodiments of the invention is as follows:

1^(st) inter- 2^(nd) inter- Second First outer 1^(st) Tie mediate core mediate 2^(nd) Tie outer layer layer layer layer layer layer layer (sealant) A B C D E F G

Core layer D of the above film structure comprises any suitable EVOH material, blended with an active oxygen barrier composition (AOBC) that comprises a blend of a thermoplastic resin (a) having carbon-carbon double bonds substantially in its main chain, a transition metal salt (b), and an oxygen barrier polymer (c). In some embodiments the active oxygen barrier composition may also include a compatibilizer (d). The oxygen barrier polymer may comprise about 70 to 99% by weight of the composition, and the thermoplastic resin having carbon-carbon double bonds typically comprises from about 1 to 30 weight % of the polymeric portion of the composition. When present, the compatibilizer typically comprises about 0.1 to 29 weight % of the total polymeric portion of the composition. Suitable active oxygen barrier compositions for some embodiments of the present invention are described in greater detail in U.S. Patent Publication Nos. 2006/0281882 and 200510153087, the contents of which are hereby incorporated by reference in their entirety. The blend of EVOH and AOBC in Layer D can be in any suitable proportion, such as from 10% to 90% EVOH and 90% to 10% AOBC, or from 20% to 80%, 30% to 70%, and 40% to 60% EVOH, and from 80% to 20%, 70% to 30%, and 60% to 40% AOBC, such as 50% EVOH and 50% AOBC.

First and second intermediate layers C and E respectively each comprise a polyamide, such as a semicrystalline polyamide such as nylon 6. The composition of layers C and E can differ, e.g. can comprise different polyamides; or can be the same. In one embodiment, layers C and E can each comprise a blend of an amorphous polyamide and a semicrystalline polyamide, in which the amorphous polyamide can comprise any suitable percent of the overall polyamide blend, e.g. less than 50 wt. %, such as less than 40 wt. %, and less than 30 wt. % of the polyamide blend of layers C and E.

First and second tie layers B and F respectively can comprise any suitable polymer or polymeric adhesive that functions to bond two layers together. Materials that can be used in embodiments of the present invention include e.g. ethylene/vinyl acetate copolymer; anhydride grafted ethylene/vinyl acetate copolymer; anhydride grafted ethylene/alpha olefin copolymer; anhydride grafted polypropylene; anhydride grafted low density polyethylene; ethylene/methyl acrylate copolymer; anhydride grafted high density polyethylene, ionomer resin, ethylene/acrylic acid copolymer; ethylene/methacrylic acid copolymer; and anhydride grafted ethylene/methyl acrylate copolymer. A suitable anhydride can be maleic anhydride. Tie layers B and F can be the same, or can differ. The choice of tie layers depends at least in part on the choice of polymer for the first and second outer layers A and G respectively.

First outer layer A comprises high density polyethylene (HDPE). Layer A comprises greater than 50% HDPE, such as greater than 60%, greater than 70%, greater than 80%, greater than 90%, and greater than 95% HDPE, such as 100% HDPE.

Second outer layer G will in some embodiments function as a sealant layer of the film. This layer comprises one or more semicrystalline olefinic polymers. Polymers that may be used for layer G include ethylene polymer or copolymer, ethylene/alpha olefin copolymer, ethylene/vinyl acetate copolymer, ionomer resin, ethylene/acrylic or methacrylic acid copolymer, ethylene/acrylate or methacrylate copolymer, low density polyethylene, high density polyethylene, propylene homopolymer, propylene/ethylene copolymer, or blends of any of these materials.

In one embodiment, first outer layer A can comprise one outermost layer of the film such that when formed into a pouch, layer A comprises the layer furthest from the packaged product; and an olefinic polymer or copolymer such as ethylene/alpha olefin copolymer (EAO) can comprise the second outer layer G of the film, such that when formed into a pouch, the EAO comprises the layer closest to the packaged product. In some embodiments, the film can be lap sealed, for example a longitudinal lap seal running the length of the pouch, such that first outer layer A is sealed to the second outer layer G. Such embodiments provide a longitudinally lap sealed pouch. More generally, pouches made from the film of the present invention can be fin sealed or lap sealed (referring to the longitudinal seal running the length of the pouch) depending on the desired configuration of the finished pouch, the equipment used, and the composition of the first and second outer layers.

A food or non-food product can be placed in a pouch made from the film of the invention, and the pouch can be sealed or otherwise closed, to make a package of the invention.

Additional materials that can be incorporated into one or both of the outer layers of the film, and in other layers of the film as appropriate, include antiblock agents, slip agents, antifog agents, etc. Other additives, such as fillers, pigments, dyestuffs, antioxidants, stabilizers, processing aids, plasticizers, fire retardants, UV absorbers, etc can also be included in the composition to impart properties desired for the particular article being manufactured.

In general, the film can have any total thickness desired, and each layer can have any thickness desired, so long as the film provides the desired properties for the particular packaging operation in which the film is used. Examples of total film thicknesses are from 2 to 8 mils, 3 to 7 mils, and 4 to 6 mils.

EXAMPLES

Several film structures in accordance with the invention were made and are identified below. Materials used were as follows.

TABLE 1 Resin Identification Material Code Tradename Or Designation Source(s) AB1 502835 ™ Ampacet AD1 PX3236 ™ LyondellBasell AD2 PLEXAR ™PX2246 LyondellBasell AD3 PURELAM ™ FASTCURE ™ Ashland 230 and 110 OB1 SOARNOL ™ SGN 017B Nippon Gohsei OB2 AP461B ™ EVALCA/Kuraray PA1 ULTRAMID ™B40LN01 BASF PE1 EXCEED ™ 1012 HA ExxonMobil PE2 DMDA-8904 NT 7 ™ Dow PE3 DOW ™2045.04 Dow PE4 ENABLE ™2005 HH ExxonMobil PE5 SURPASS ™ HPs 167 AB Nova Chemicals PE6 SURPASS ™ EX-HPs667 AB 01 Nova Chemicals PET1 MYLAR ™ 822 DuPont AB1 is a masterbatch having about 80%, by weight of the masterbatch, of T60-500-119 ™, a high density polyethylene available from Innovene with a density of 0.961 grams/cc; about 16%, by weight of the masterbatch, of SILTON JC30A ™, a sodium calcium aluminum silicate, NaCaAl(Si₂O₇); and about 4 w %, by weight of the masterbatch, of CLEAR Block80 ™ talc, an antiblocking agent. AD1 is a maleic anhydride-modified linear low density polyethylene with a density of 0.921 grams/cc. AD2 is a maleic anhydride-modified high density polyethylene with a melt flow rate of 0.60 g/10 min per ASTM D1238, a density of 0.95 g/cc per ASTM D1505 and a Vicat softening point of 124 degrees Celsius per ASTM 1525. AD3 is a solventless polyurethane adhesive made up of 67% a polyol - polyester coreactant (PURELAM ™ FASTCURE ™ 230), and 33% of an aliphatic isocyanate (PURELAM ™ FASTCURE ™ 110). OB1 is an ethylene/vinyl alcohol copolymer (EVOH) with about 27.5 mole % ethylene. OB2 is an active oxygen barrier composition that includes an EVOH (EVAL ™ F171B) compounded with an oxygen scavenging resin having carbon-carbon double bonds substantially in its main chain, and a transition metal (cobalt) salt as a catalyst. PA1 is a nylon 6 (poly(caprolactam)). PE1 is a single-site catalyzed (homogeneous) ethylene/1-hexene copolymer with a density of 0.912 grams/cc. PE2 is a high density polyethylene with a density of 0.952 grams/cc. PE3 is a Ziegler/Natta catalyzed (heterogeneous) ethylene/octene-1 copolymer with a 6.5 weight % octene content, and a density of 0.920 grams/cc. PE4 is a single-site catalyzed (homogeneous) ethylene/1-hexene copolymer with a density of 0.920 grams/cc. PE5 is a high density polyethylene resin with a density of 0.966 grams/cc. PE6 is a high density polyethylene resin with a density of 0.967 grams/cc. PET1 is a biaxially oriented monolayer film, 0.5 mils thick, of a polyethylene terephthalate that has been chemically primed on one side.

All compositional percentages given herein are by weight, unless indicated otherwise. The following films were made by otherwise conventional coextrusion techniques.

Example 1

Layers G A B D F 70% PE3 + 98% PE5 + 80% AD1 + C 50% OB1 + E 80% AD1 + 22% PE4 + 2% AB1 20% PE1 PA1 50% OB2 PA1 20% PE1 8% AB1 Layer 0.968 0.919 1.14 1.174 1.14 0.919 0.930 density (grams/cc) Weight % 22% 9% 10% 11% 10% 8% 30%

Example 2

Layers G A B D F 70% PE3 + 98% PE5 + 80% AD2 + C 50% OB1 + E 80% AD1 + 22% PE4 + 2% AB1 20% PE6 PA1 50% OB2 PA1 20% PE1 8% AB1 Layer 0.968 0.953 1.14 1.174 1.14 0.919 0.930 density (grams/cc) Weight % 22% 9% 10% 11% 10% 8% 30%

Example 3

Layers G A B D F 70% PE3 + 98% PE5 + 80% AD2 + C 50% OB1 + E 80% AD2 + 22% PE4 + 2% AB1 20% PE6 PA1 50% OB2 PA1 20% PE6 8% AB1 Layer 0.968 0.953 1.14 1.174 1.14 0.953 0.930 density (grams/cc) Weight % 22% 9% 10% 11% 10% 8% 30%

Layers G A B D F 46% PE3 + 98% PE5 + 80% AD2 + C 50% OB1 + E 80% AD2 + 46% PE5 + 2% AB1 20% PE6 PA1 50% OB2 PA1 20% PE6 8% AB1 Layer 0.968 0.953 1.14 1.174 1.14 0.953 0.951 density (grams/cc) Weight % 22% 9% 10% 11% 10% 8% 30%

Example 5

Layers A B D F G 98% PE5 + 80% AD2 + C 50% OB1 + E 80% AD2 + 98% PE5 + 2% AB1 20% PE6 PA1 50% OB2 PA1 20% PE6 2% AB1 Layer 0.968 0.953 1.14 1.174 1.14 0.953 0.973 density (grams/cc) Weight % 22% 9% 10% 11% 10% 8% 30%

Film Analysis and Procedures for Determining Physical Properties

Samples of the films of Examples 1 to 5 were analyzed for Moisture Vapor Transmission Rate (MVTR), Instrumented Impact, and Elastic Modulus properties.

1. Moisture Vapor Transmission Rate (MVTR).

Films of the invention are characterized by relatively low MVTR, as measured by ASTM F1249. One side of a film sample was exposed to water vapor under controlled conditions, and the steady-state transmission rate was measured at the opposite surface of the film. The conditions used were 100° F. and 100% RH. Three film samples were used for each example. Resulting MVTR values are shown in Table 2.

TABLE 2 Exam- % MVTR (g/100 in² · d)² Gauge ple HDPE¹ MVTR Mean StDev (mils) 1 20.75 0.058 0.0580 0.0030 5.33 0.055 5.28 0.061 5.16 2 29.2 0.055 0.0520 0.0030 5.53 0.049 5.66 0.052 5.43 3 36.66 0.045 0.0463 0.0023 5.29 0.049 5.26 0.045 5.32 4 49.33 0.032 0.0467 0.0131 5.15 0.057 5.38 0.051 5.45 5 62.43 0.048 0.0453 0.0023 5.25 0.044 5.45 0.044 5.48 ¹The total weight % of HDPE for each of Examples 1 to 5 ²Three replicate measurements were made for MVTR values for Examples 1 to 5.

Moisture permeability, i.e. the MVTR values of the samples of Table 2 normalized to the actual gauge thickness of the film samples, is shown in Table 3.

TABLE 3 Exam- % Gauge Permeability ple HDPE (mils) (gram · mil/100 in² · d) Mean StDev 1 20.75 5.33 0.30914 0.3048 0.0128 5.28 0.2904 5.16 0.31476 2 29.2 5.53 0.30415 0.2880 0.0143 5.66 0.27734 5.43 0.28236 3 36.66 5.29 0.23805 0.2451 0.0110 5.26 0.25774 5.32 0.2394 4 49.33 5.15 0.1648 0.2498 0.0750 5.38 0.30666 5.45 0.27795 5 62.43 5.25 0.252 0.2443 0.0067 5.45 0.2398 5.48 0.24112 One mil = 0.001 inches.

2. Instrumented Impact

Films of the invention are characterized by relatively high instrumented impact, as measured by ASTM D3763 using the Dynatup test method. A test film was loaded into the environmental chamber and allowed to equilibrate to the chamber temperature. A dart having a specified tup (having an impact head and a load cell) was dropped under gravity (Tup 7037 was used in these tests). Maximum load and total energy are reported along with the mode of the failure. Impact was measured at 40° F. (refrigeration temperature) and 73° F. (room temperature). Resulting values are shown in Tables 4 and 5.

TABLE 4 (40° F.) 40° F. Max. Load Total energy Exam- (lbs)¹ (lb · ft)³ Failure ple % HDPE Mean StDev Mean StDev mode* 1 20.75 21.78 9.46 0.34 0.2 1nb, 2br, 1sh 2 29.2 30.67 0.79 0.41 0.03 4 sh 3 36.66 32.09 3.23 0.64 0.09 3 br, 1 sh 4 49.33 26.15 5.91 0.34 0.17 3 sh 5 62.43 26.14 1.32 0.29 0.03 3 sh ³Four replicate measurements were made for Max. Load and Total energy values for each of Examples 1 to 3; three replicate measurements were made for Max. Load and Total energy values for each of Examples 4 and 5.

TABLE 5 (73° F.) 73° F. Max Load Total energy Exam- (lbs)⁴ (lb · ft)⁴ Failure ple % HDPE Mean StDev Mean StDev mode* 1 20.75 28.55 3.05 0.64 0.1 4 br 2 29.2 27.2 1.14 0.59 0.04 4 br 3 36.66 26.62 2.07 0.58 0.1 2 br, 2 sh 4 49.33 27.22 1.14 0.57 0.1 2 br, 2 sh 5 62.43 26.73 1.38 0.44 0.09 4 sh ⁴Four replicate measurements were made for Max. Load and Total energy values for each of Examples 1 to 5. *for the failure mode for both Tables 4 and 5: nb = no break br = specimen broke (ductile) sh = specimen shattered (brittle)

3. Elastic Modulus

Films of the invention are characterized by relatively high Elastic Modulus (or Young's Modulus), as measured by ASTM D882, for both the longitudinal, i.e. machine direction (MD) and the transverse direction (TD). A plastic film sample was uniaxially deformed by the application of a tensile stress. The strain corresponding to the applied stress is measured to generate a stress-strain curve. The initial slope of the curve is the elastic modulus, an indicator of film stiffness. Typically, as the modulus of a material increases, the impact strength decreases. Modulus was measured at room temperature and 50% RH. Resulting elastic modulus values are shown in Table 6.

TABLE 6 Exam- % MD Modulus⁵ (kpsi) TD Modulus⁵ (kpsi)⁶ ple HDPE Mean StDev Mean StDev 1 20.75 147 18.8 153 5.07 2 29.2 177 6.02 185 3.1 3 36.66 182 2.78 188 4.4 4 49.33 198 6.24 208 8.47 5 62.43 206 9.81 230 15.9 ⁵Four replicate measurements were made for MD Modulus values for each of Examples 1, 3, and 5; eight replicate measurements were made for MD Modulus values for each of Examples 2 and 4, and for all the TD Modulus values of Examples 1 to 5. ⁶kpsi = thousand pounds per square inch.

Comparative Example 6

A blown film was made comprising 100% HDPE, having a final thickness of 3.6 mils. The film exhibited MVTR values of 0.06 g/100 in²·d. Thus, films of the invention, utilizing less than and in some cases considerably less than the equivalent total thickness of HDPE, provided either substantially equivalent or else superior moisture barrier performance.

Laminate Made from Film of the Invention

In some embodiments, film of the invention is laminated, for example by a polyurethane adhesive, to a trap-printed polyethylene terephthalate (PET) monolayer film. The PET film is typically adhered to the first outer layer A of the film. In these embodiments, in addition to the properties disclosed above, laminates of the invention provide printing for applications where printed indicia on the package is desired. Prophetic examples of laminates according to the invention are:

Example 7

Example 1//trap-printed PET

Example 8

Example 2//trap-printed PET

Example 9

Example 3//trap-printed PET

Example 10

Example 4//trap-printed PET

Example 11

Example 5//trap-printed PET

where in each case the double slash marks indicate the adhesive connection of the film of the invention with the trap-printed PET film, and the first outer layer is adhesively joined to the printed surface of the PET film.

Example 12

A laminate was made having the construction:

Example 3/AD3/unprinted PET1

where the film of Example 3 was laminated, at the first outer layer, to a 0.5 mil thick PET monolayer film, by means of the adhesive AD3. Measured physical properties of Example 12, using similar protocol and terms as for Examples 1 to 5, were as follows:

TABLE 7 Exam- % MVTR (g/100 in² · d) Gauge ple HDPE¹ MVTR Mean StDev (mils) 12 32.23 0.05 0.0467 0.0031 5.51 0.046 5.28 0.044 5.47 ¹The total weight % of HDPE for Example 12

TABLE 8 Exam- % Gauge Permeability ple HDPE (mils) (gram · mil/100 in² · d) Mean StDev 12 32.23 5.51 0.2755 0.2530 0.0195 5.28 0.24288 5.47 0.24068

TABLE 9 (40° F.) 40° F. Max. Load Total energy Exam- (lbs) (lb · ft) Failure ple % HDPE Mean StDev Mean StDev mode 12 32.23 39.36 2.1 0.56 0.07 4sh

TABLE 10 (73° F.) 73° F. Max Load Total energy Exam- (lbs)⁴ (lb · ft)⁴ Failure ple % HDPE Mean StDev Mean StDev mode* 12 32.23 34.57 1.19 0.6 0.06 1 br, 3 sh

TABLE 11 Exam- % MD Modulus (kpsi) TD Modulus (kpsi) ple HDPE Mean StDev Mean StDev 12 32.23 207 1.57 217 2.78

End-Use Applications

Films and laminates of the present invention can be pre-made into pouches, e.g. for retort packaging, or alternatively can be converted into packages using vertical/form/fill/seal (VFFS) equipment and processes. Examples of the latter include aseptic, hot fill, and retort processes. More generally, films and laminates of the invention can be used in VFFS processes to package food and non-food products, including fruit pieces such as pineapple; beef stew; tomatoes; soups; both high and low-acid foods.

The Aseptic Process

Aseptic packaging typically involves the sterilization of liquid foods and beverages outside the package, and separate sterilization of the packaging material, to produce a shelf stable package. Ultra high temperature is used to rapidly heat the food product, followed by cooling of the product, before the product is put into the pouch or other container formed from the packaging material. Processing times for the product are generally 3 to 15 seconds; temperatures range from about 195° F. to 285° F. An example of a commercially available aseptic form/fill/seal equipment system is the ONPACK™ KAF 2000 system having a film sterilization section including a tank for hydrogen peroxide, a drying chamber, a form/fill/seal section, and a unit which supplies and circulates hydrogen peroxide and controls temperature, air pressure etc. Film is continuously sterilized by hydrogen peroxide set at a temperature of between 60° C. and 80° C. in a chemical tank. After film leaves this tank, hot air at a temperature of between 60° C. and 80° C. is used to dry out the film to remove hydrogen peroxide from the film. Temperature and flow level for the hydrogen peroxide is controlled by steam to raise temperature, and water is supplied for cooling. Piping between the food sterilizer and the packaging unit can be initially sterilized using steam heat or hot water. After film exits the peroxide tank, the film is scraped by plates and by an air knife to make it easy to dry.

The Hot Fill Process

In a “hot fill” VFFS process, flowable products such as soups, sauces, jellies, beverages and other liquefied foods are introduced at elevated temperatures (typically from 170° F. to 210° F.) through the central, vertical fill tube of VFFS equipment and into a formed tubular film that has been heat-sealed transversely at its lower end. After being filled, the package, in the form of a pouch, is completed by transversely heat-sealing the upper end of the tubular segment, and severing the pouch from the tubular film above it, usually by applying sufficient heat to melt through the tube above the newly formed upper heat-seal.

The Retort Process

Retort is a cooking process that uses heat and pressure to cook food in its sealed package. Retorting involves subjecting a product packaged in a flexible film, such as a food product packaged in a flexible film, to sterilizing conditions of high temperature (i.e., of from 212° F. to 300° F.) for a period of from 10 minutes to 3 hours or more, in the presence of water, steam, or pressurized steam. Retorting is usually carried out at a temperature of from 240° F. to 260° F. for a period of from 10 minutes to 3 hours, under high humidity, and at elevated pressure.

The present application is directed in various embodiments to the subject matter described below. These are optional embodiments of any of the first, second, and third aspects of the invention as described hereinabove in the Summary of the Invention, and for each aspect, these features can be suitably included alone or in any suitable combination of these features:

-   -   the thermoplastic resin of the active oxygen barrier composition         of the coextruded multilayer blown film comprises at least one         of the units represented by formula (I) and formula (II):

wherein R1, R2, R3 and R4 are the same or different, a hydrogen atom, an alkyl group that may be substituted, an aryl group that may be substituted, an alkylaryl group that may be substituted, —COOR5, —OCOR6, a cyano group or a halogen atom, and R3 and R4 may together form a ring via a methylene group or an oxymethylene group, where R5 and R6 are an alkyl group that may be substituted, an aryl group that may be substituted or an alkylaryl group that may be substituted.

-   -   the blend of EVOH and AOBC in the core layer of the coextruded         multilayer blown film can be in any of the following         proportions: from 10% to 90% EVOH and 90% to 10% AOBC, or from         20% to 80%, 30% to 70%, and 40% to 60% EVOH, and from 80% to         20%, 70% to 30%, and 60% to 40% AOBC, such as 50% EVOH and 50%         AOBC.     -   the polyamide of each of the first and second intermediate         layers of the coextruded multilayer blown film comprises nylon         6.     -   from 25% to 55%, 30% to 50%, and 32% to 40% of the coextruded         multilayer blown film comprises high density polyethylene.     -   the coextruded multilayer blown film is characterized by a         moisture vapor transmission rate (ASTM F1249) of from 0.03 to         0.06, such as from 0.04 to 0.05 grams/100 square inches·day.     -   the coextruded multilayer blown film is characterized by an         overall film thickness normalized moisture vapor transmission         rate (ASTM F1249), or moisture permeability, of from 0.15 to         0.31, such as from 0.20 to 0.25 grams·mil/100 square inches·day.     -   the coextruded multilayer blown film is characterized by an         instrumented impact (ASTM D3763) maximum load at 40° F. of from         20 to 35 lbs., such as from 25 to 35 lbs.     -   the coextruded multilayer blown film is characterized by an         instrumented impact (ASTM D3763) maximum load at 73° F. of from         25 to 30 lbs.     -   the coextruded multilayer blown film is characterized by an         instrumented impact (ASTM D3763) total energy at 40° F. of from         0.30 to 0.70 lb·ft, such as from 0.35 to 0.65 lb·ft.     -   the coextruded multilayer blown film is characterized by an         instrumented impact (ASTM D3763) total energy at 73° F. of from         0.40 to 0.70 lb·ft, such as from 0.50 to 0.65 lb·ft.     -   the coextruded multilayer blown film is characterized by an         elastic modulus (ASTM D882) in the machine direction of from 145         to 210 kpsi, such as from 160 to 200 kpsi.     -   the coextruded multilayer blown film is characterized by an         elastic modulus (ASTM D882) in the transverse direction of from         150 to 230 kpsi, such as from 170 to 200 kpsi.     -   the first outer layer and the first tie layer of the coextruded         multilayer blown film each comprises high density polyethylene.     -   the first outer layer and the first tie layer of the coextruded         multilayer blown film each comprises at least 80%, by weight of         the respective layer, or at least 90%, by weight of the         respective layer, high density polyethylene.     -   the first outer layer and the first and second tie layers of the         coextruded multilayer blown film each comprises high density         polyethylene.     -   the first outer layer and the first and second tie layers of the         coextruded multilayer blown film each comprises at least 80%, by         weight of the respective layer, or at least 90% by weight of the         respective layer, high density polyethylene.     -   the first outer layer, the first and second tie layers, and the         second outer layer of the coextruded multilayer blown film each         comprises high density polyethylene.     -   the first outer layer, and the first and second tie layers of         the coextruded multilayer blown film each comprises at least         80%, by weight of the respective layer, or at least 90%, by         weight of the respective layer, high density polyethylene, and         the second outer layer of the coextruded multilayer blown film         comprises from 20% to 60%, by weight of the second outer layer,         high density polyethylene.     -   the olefinic polymer of the second outer layer of the coextruded         multilayer blown film is selected from the group consisting of         -   a) a blend of a heterogeneous ethylene/alpha-olefin             copolymer having a density of less than 0.940 grams/cc and a             homogeneous ethylene/alpha-olefin copolymer having a density             of less than 0.940 grams/cc;         -   b) a blend of a heterogeneous ethylene/alpha-olefin             copolymer having a density of less than 0.940 grams/cc and a             high density polyethylene; and         -   c) high density polyethylene.     -   at least one of the first and second tie layers of the         coextruded multilayer blown film comprises an anhydride grafted         polymer.     -   at least one of the first and second tie layers of the         coextruded multilayer blown film comprises an anhydride grafted         high density polyethylene.     -   100% of at least one of the first and second tie layers of the         coextruded multilayer blown film comprises an anhydride grafted         high density polyethylene.     -   each of the first and second tie layers of the coextruded         multilayer blown film comprises a blend of     -   a) from 55% to 90% by weight of an anhydride grafted high         density polyethylene; and     -   b) from 10% to 45% by weight of high density polyethylene.     -   at least 80% of at least one of the first and second tie layers         of the coextruded multilayer blown film comprises high density         polyethylene.     -   the coextruded multilayer blown film is adhered, at its first         outer layer, to a film comprising polyethylene terephthalate.     -   the coextruded multilayer blown film is adhered, at its first         outer layer, to a film comprising polyethylene terephthalate         that is printed.     -   the coextruded multilayer blown film is adhered, at its first         outer layer, to a film comprising polyethylene terephthalate         that is trap-printed.     -   the coextruded multilayer blown film exhibits a free shrink         (ASTM D 2732) at 200° F. of less than 5%, such as less than 4%,         less than 3%, and less than 2%, in each of the longitudinal and         transverse directions.     -   the coextruded multilayer blown film, and the package, are         absent a metallized layer.     -   the coextruded multilayer blown film, and the package, are         microwaveable.     -   the coextruded multilayer blown film is transparent.     -   the package is in the form of a stand-up pouch.     -   the package is in the form of a pre-made pouch adapted to be         exposed, after a food product is disposed in the pouch and the         pouch is sealed, to retort conditions. 

1.-20. (canceled)
 21. A coextruded multilayer blown film comprising: a) a core layer comprising a blend of i) ethylene/vinyl alcohol copolymer, and ii) an active oxygen barrier composition comprising a blend of a thermoplastic resin having carbon-carbon double bonds substantially in its main chain, a transition metal salt, and an oxygen barrier polymer; b) a first and second intermediate layer each comprising polyamide; c) a first outer layer comprising high density polyethylene; d) a second outer layer comprising an olefinic polymer; e) a first tie layer adhering the first intermediate layer to the first outer layer; and f) a second tie layer adhering the second intermediate layer to the second outer layer; wherein from 20% to 65% by weight of the coextruded multilayer blown film comprises high density polyethylene.
 22. The coextruded multilayer blown film of claim 21 wherein the thermoplastic resin of the active oxygen barrier composition comprises at least one of the units represented by formula (I) and formula (II):

wherein R1, R2, R3 and R4 are the same or different, a hydrogen atom, an alkyl group that may be substituted, an aryl group that may be substituted, an alkylaryl group that may be substituted, —COOR5, —OCOR6, a cyano group or a halogen atom, and R3 and R4 may together form a ring via a methylene group or an oxymethylene group, where R5 and R6 are an alkyl group that may be substituted, an aryl group that may be substituted or an alkylaryl group that may be substituted.
 23. The coextruded multilayer blown film of claim 21 wherein the polyamide of each of the first and second intermediate layers comprises nylon
 6. 24. The coextruded multilayer film of claim 21 wherein the olefinic polymer of the second outer layer is selected from the group consisting of a) a blend of a heterogeneous ethylene/alpha-olefin copolymer having a density of less than 0.940 grams/cc, and a homogeneous ethylene/alpha-olefin copolymer having a density of less than 0.940 grams/cc; b) a blend of a heterogeneous ethylene/alpha-olefin copolymer having a density of less than 0.940 grams/cc, and a high density polyethylene; and c) high density polyethylene.
 25. The coextruded multilayer film of claim 21 wherein at least one of the first and second tie layers comprises an anhydride grafted polymer.
 26. The coextruded multilayer film of claim 25 wherein at least one of the first and second tie layers comprises an anhydride grafted high density polyethylene.
 27. The coextruded multilayer film of claim 26 wherein each of the first and second tie layers comprises a blend of a) from 55% to 90% by weight of an anhydride grafted high density polyethylene; and b) from 10% to 45% by weight of high density polyethylene.
 28. The coextruded multilayer blown film of claim 21 wherein the first outer layer and the first tie layer each comprises at least 80%, by weight of the respective layer, high density polyethylene.
 29. The coextruded multilayer blown film of claim 21 wherein the first outer layer and the first and second tie layers each comprises at least 80%, by weight of the respective layer, high density polyethylene.
 30. The coextruded multilayer blown film of claim 21 wherein the first outer layer and the first and second tie layers each comprises at least 80%, by weight of the respective layer, high density polyethylene; and the second outer layer comprises from 20% to 60%, by weight of the second outer layer, high density polyethylene.
 31. A package comprises: a) a food product, and b) a hermetic pouch in which the food product is disposed, the hermetic pouch having a longitudinal seal and transverse heat seals, the pouch comprising a coextruded multilayer blown film comprising (i) a core layer comprising a blend of ethylene vinyl alcohol copolymer, and an active oxygen barrier composition comprising a blend of a thermoplastic resin having carbon-carbon double bonds substantially in its main chain, a transition metal salt, and an oxygen barrier polymer; (ii) a first and second intermediate layer each comprising polyamide; (iii) a first outer layer comprising high density polyethylene; (iv) a second outer layer comprising an olefinic polymer; (v) a first tie layer adhering the first intermediate layer to the first outer layer; and (vi) a second tie layer adhering the second intermediate layer to the second outer layer; wherein from 20% to 65% by weight of the coextruded multilayer blown film comprises high density polyethylene.
 32. The package of claim 31 wherein the thermoplastic resin of the active oxygen barrier composition comprises at least one of the units represented by formula (I) and formula II:

wherein R1, R2, R3 and R4 are the same or different, a hydrogen atom, an alkyl group that may be substituted, an aryl group that may be substituted, an alkylaryl group that may be substituted, —COOR5, —OCOR6, a cyano group or a halogen atom, and R3 and R4 may together form a ring via a methylene group or an oxymethylene group, where R5 and R6 are an alkyl group that may be substituted, an aryl group that may be substituted or an alkylaryl group that may be substituted.
 33. The package of claim 31 wherein the polyamide of each of the first and second intermediate layers comprises nylon
 6. 34. The package of claim 31 wherein the olefinic polymer of the second outer layer is selected from the group consisting of a) a blend of a heterogeneous ethylene/alpha-olefin copolymer having a density of less than 0.940 grams/cc, and a homogeneous ethylene/alpha-olefin copolymer having a density of less than 0.940 grams/cc; b) a blend of a heterogeneous ethylene/alpha-olefin copolymer having a density of less than 0.940 grams/cc, and a high density polyethylene; and c) high density polyethylene.
 35. The package of claim 31 wherein at least one of the first and second tie layers comprises an anhydride grafted polymer.
 36. The package of claim 35 wherein at least one of the first and second tie layers comprises an anhydride grafted high density polyethylene.
 37. The package of claim 36 wherein at least one of the first and second tie layers comprises a blend of a) from 55% to 90% by weight of an anhydride grafted high density polyethylene; and b) from 10% to 45% by weight of high density polyethylene.
 38. The package of claim 31 wherein the first outer layer and the first tie layer each comprises at least 80%, by weight of the respective layer, high density polyethylene.
 39. The package of claim 31 wherein the first outer layer and the first and second tie layers each comprises at least 80%, by weight of the respective layer, high density polyethylene.
 40. The package of claim 31 wherein the first outer layer and the first and second tie layers each comprises at least 80%, by weight of the respective layer, high density polyethylene; and the second outer layer comprises from 20% to 60%, by weight of the second outer layer, high density polyethylene. 